Films For Nonlinear Optical Applications Research Articles

Characterization of sol gel derived spin coated copper incorporation of CdS films for nonlinear optical applications

The sol-gel derived spin-coated Copper (Cu) doped cadmium sulphide (CdS) thin films were deposited on glass substrates. The structural, optical, electrical, and non-linear properties of the films have been investigated in detail. The crystal structure of the Cu-doped CdS films was found to be the hexagonal phase, and an improvement in the crystallinity was observed. The optical absorbance was found to change with deposition parameters, and the bandgap of the films was found to be 2.3 eV, which varied with doping and annealing. The photoluminescent properties of the films showed green and near band edge emission. The electrical characteristics of the Cu-doped CdS films were investigated by Hall effect measurements. The copper doped CdS thin films exhibited prominent NLO properties. The NLA coefficients β obtained are of the order of 10−9m/W. The nonlinear refractive index n2 and nonlinear susceptibility χ (3) values were found to be of the order of 10−11 esu.

Dopant and Annealing Temperature of Copper Incorporation Studies in CDS Films for Nonlinear Optical Applications

Dopant and Annealing Temperature of Copper Incorporation Studies in CDS Films for Nonlinear Optical Applications

Characterization of Sn doped vanadium oxide thin films for nonlinear optical applications

Tin doped vanadium oxide thin films were deposited on the glass substrate by thermal evaporation technique with 3%, 6%, 9% and 12% by weight of SnO2. The deposited films were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectrometer, atomic force microscopy (AFM) and UV-Vis spectroscopy. The amorphous nature of all deposited films was confirmed by the X-ray diffraction method. The elemental analysis of the films was confirmed by EDX analysis. UV–Vis spectroscopy is used for optical analysis such as optical transmission, absorption and band gap analysis of the thin films in the range 300–800 nm. The nonlinear optical parameters of the deposited thin films were estimated by empirical relations. Based on all these characterizations, the films are practical for linear and nonlinear applications.

Synthesis and Characterization of Dye-Doped Polymer Films for Non-linear Optical Applications

Synthesis and Characterization of Dye-Doped Polymer Films for Non-linear Optical Applications

Sprayed nanocrystalline ZMS thin films for nonlinear optical device applications

Growth and characterization of novel Zn(1-x)MgxS (ZMS) thin films for the nonlinear optical applications are reported here. ZMS thin films were deposited by industrial friendly spray pyrolysis method at optimized deposition conditions. XRD showed good crystallinity having crystallite size in the range 4.6–11 nm. It also confirmed the presence of mixed phases of zinc blende and wurtzite having strong orientation along (111) and (104) planes respectively. All the films have shown transmittance in the range 75%–90%. Detailed analysis of the transmittance data revealed a slight increase in the band gap from 3.42 eV to a maximum of 3.48 eV for 4 at% Mg doped thin films. Photoluminescence study confirmed the presence of intermediate bands in the doped thin films. Substantial change in third order optical susceptibility (χ(3)) and nonlinear refractive index (n2) values were observed for the doped films as compared to pristine samples. Remarkably, there was a flip from saturable absorption (SA) into the reverse saturation absorption (RSA) for the doped films. Z-scan studies showed that the spray deposited ZMS thin films are suitable for the nonlinear devices such as optical limiters and modulators.

A novel approach for tailoring structural, morphological, photoluminescence and nonlinear optical features in spray coated Cu:ZnO nanostructuresviae-beam

We present electron beam induced modifications on structural, morphological, and optical properties of spray coated Cu doped ZnO thin films for nonlinear optical applications.

Laser printing of azo-derivative thin films for non-linear optical applications

The use of laser-based processing is presented here for the transfer of azo-derivatives, for optoelectronics assembly applications. Laser-printing techniques are also adequate tools for rapid prototyping of diverse materials, since they avoid the usage of solutions, moulds, lithography masks, etc. Here, we present a study on the laser-induced forward transfer (LIFT) and printing of micrometric-sized pixels (350μm×350μm), by using matrix-assisted pulsed laser evaporation (MAPLE) deposited thin film donors. Due to their particular optical properties, i.e. second harmonic generation, optical limiting and all-optical poling, and with applications in optoelectronics and sensor development, azo-dyes have been intensively studied in bulk or as thin films. The influence of a metallic dynamic release layer (DRL) during LIFT is investigated.

Azo dye doped polymer films for nonlinear optical applications

Azo dye doped polymer films were prepared on glass substrates using spin-coating technique. FTIR, UV-Vis spectra and PL measurements were recorded to characterize the structure of the metanil yellow doped PVA films. Surface morphology and thickness of the films were studied using AFM and FESEM. The magnitude of both real and imaginary parts of third-order nonlinear susceptibility χ 3 of metanil yellow were determined by the Z-scan technique. The nonlinear refractive index n 2 and the nonlinear absorption coefficient β of the azo dye doped polymer films were calculated respectively. The real part of the third-order susceptibility χ 3 is much larger than its imaginary part indicating that the third-order optical response of the metanil yellow doped PVA films is dominated by the optical nonlinear refractive behavior.

Nanocomposite thin films of Ga 5Sb 10Ge 25Se 60 chalcogenide glass for optical limiting applications

We report a low-cost, scalable method to fabricate optical grade composite thin films for nonlinear optical applications. The transmission and reflection spectra of prepared Ga 5Sb 10Ge 25Se 60/PVA composite films were investigated. Optical band gap of the thin films were calculated using Tauc’s extrapolation method. The band gap of the nanocomposite thin films were found to be tunable depending on the grain size of the films. Nonlinear optical characterization of samples were studied by the Z-scan technique using an Nd:YAG laser (532 nm, 7 ns, 10 Hz). Sequential Z-scan traces were made in four regimes of intensity for films with three different grain sizes. The Z-scan spectra reveal a strong nonlinear absorption depending on the grain size of the films suggesting that the new materials are promising candidates for the development of nonlinear optical devices and are extremely perspective as optical limiters of intense short pulse radiation.

Investigations of the Correlation between the Preparation Method and the Properties of Anilinic Derivative Functionalised Polymer Thin Films for Non-Linear Optical Applications

This paper presents a study of two copolymers, maleic anhydride and methylmethacrilate/maleic anhydride and vinyl benzyl chloride, functionalised with polar chromophoric groups such as 2,4 dinitroaniline. Thin films have been prepared by vacuum evaporation and spin coating methods on silicon and glass substrates. UV-VIS, FTIR, XRD and Photoluminescence Spectroscopy have been used to comparatively investigate the effect of the preparation method on the properties of the thin films obtained with functionalized copolymer. SEM has evidenced differences in the morphologies of the layers suggesting a degradation of the polymeric chain during the evaporation process to fragments that conserve unchanged the chromophoric group. This explains the presence of two types of non-linear phenomena, the second harmonic emission and two-photon luminescence emissions for both vacuum evaporated and spin coated films.

High-Quality Organic Single Crystalline Thin Films for Nonlinear Optical Applications by Vapor Growth

We report on the production of organic single crystalline thin films for integrated nonlinear optical applications by a vapor growth technique. The configurationally locked polyene chromophore 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) that was used exhibits a noncentrosymmetric crystalline arrangement with monoclinic point group symmetry 2. It shows a second harmonic generation signal of about 2 orders of magnitude greater than that of urea. The grown DAT2 films are single crystalline and exhibit good optical quality and suitable size (area of ∼5 × 3 mm2 and the thickness in the range of 0.2−5 μm) for fabrication of photonic devices. Growth rates of a few hours have been achieved. Furthermore, the edges of the films are sharp and flat, which greatly reduces the additional processing requirements for applications.

Molecular Lego: non-centrosymmetric Langmuir-Blodgett films for nonlinear optical applications

The cationic dye, E-N-hexadecyl-4-[2-(4-octadecyloxynaphthyl)ethenyl]quinolinium bromide, has hydrophobic n-alkyl groups at opposite ends of a wide-bodied donor-(π-bridge)-acceptor chromophore. When deposited by the Langmuir-Blodgett technique at 40 mN m -1 , the LB monolayer has a thickness of 4.9 nm, this being compatible with the molecular length if the dye adopts a stretched rather than a U-shaped conformation. In contrast, the mean thickness within multilayer films is 2.5 nm layer -1 , This discrepancy arises from an interdigitating layer arrangement, not applicable to the monolayer, as well as a slightly different molecular tilt in the bulk film. The second-harmonic intensity increases quadratically with the number of deposited layers, i.e. as I 2ω (N) = I 2ω (1) N 2 , Thus, it is the first example of a Lego-type structure with non-centrosymmetric alignment of the optically nonlinear chromophores.

Novel nonlinear optical polymers based on poly(1,4-phenylenevinylene)

A novel poly(1,4-phenylenevinylene) (PPV) derivative containing a nonlinear optical (NLO) moiety was synthesizedvia the methoxy-precursor pathway to give a highly rigid structure which still maintained good processability. Poly[2-butoxy-5-(2-{ethyl-[4-(4-nitrophenyldiazenyl)phenyl]amino}ethoxy)-1,4-phenylenevinylene] (PBDR1PV), containing a Disperse Red 1 (DR1)-type chromophore, was characterized by conventional spectroscopic methods (UV–VIS, FT-IR, NMR) and by thermal analyses. The synthetic approach has been applied for the preparation of high optical quality films for nonlinear optical applications. PBDR1PV films showed a high resonant d33 value of 50 pm V–1 when measured using the second harmonic generation (SHG) method. The nonlinearity of PBDR1PV was very stable at 90 °C for a month without detectable loss. In addition to second-order NLO properties, the PBDR1PV film showed third-order NLO properties simultaneously and the measured chi;(3) value was found to be 2.5×10–12 esu.

Growth of beta barium borate (β-BaB 2O 4) thin films for nonlinear optical applications

We have prepared crystalline beta barium borate, β-BaB 2O 4 (the so-called BBO), thin films on several kinds of substrates using pulsed laser deposition (PLD) and opposed-targets magnetron sputtering (OTMS) techniques. From the measurement of X-ray diffraction, we have found that the crystallinity of the BBO film grown by both techniques is highly dependent on the deposition temperature and the choice of the substrates. There is a different phase transition temperature for the BBO films grown on different substrates and by different deposition techniques. The best films obtained were the ones grown on a sapphire (0 0 0 1) substrate at a deposition temperature of 800°C by PLD and 700°C by OTMS, which show a single X-ray diffraction (0 0 6) peak normal to the surface of the film. The second harmonic generation (SHG) signal of these films reveals a 6-fold symmetry with a large magnitude contrast between its maximum (1.2 pm/V) and minimum (0.2 pm/V).

Solid state coagulation of rigid-rod polymer thin films

A novel coagulation processing scheme has been developed to fabricate optical quality polymer thin films for non-linear optical applications. In this process, termed solid state coagulation, an optically isotropic polymer solution is rapidly frozen into a solid mixture to preserve the molecular dispersion of the polymer in the solvent. It is then coagulated at a cryogenic temperature in a proper coagulant to extract the frozen solvent without disrupting the molecular distribution of the polymer. Thin films of rigid-rod poly( p-phenylene benzobisthiazole) (PBZT) prepared by this technique showed an optical attenuation coefficient of about 300 cm −1 (or 1300 db cm −1), significantly lower than the 990 cm −1 (or 4300 db cm −1) obtained from the thin films prepared by the conventional solution-state coagulation process. Wide angle X-ray scattering confirmed that the domain structures in the solid-state coagulated PBZT thin films are smaller and less ordered than those in the solution-state coagulated thin films. This solid state coagulation processing scheme is particularly valuable for polymer systems, such as rigid-rod polymers, ladder polymers, crystalline polymers and polymer blends of incompatible systems, which cannot be processed with significant optical clarity by melt processing or solution casting.

Poling dynamics and investigation into the behavior of trapped charge in poled polymer films for nonlinear optical applications

The behavior of surface and trapped charge that originate during contact electric-field poling of a model guest–host nonlinearly active polymer has been investigated. Charge effects in thin films of para-nitroaniline doped polymethylmethacrylate were studied during and after the poling process by simultaneous measurement of the current through the poling circuit and the second harmonic generation (SHG) signal from the polymer system. The poling current present in a fresh sample was found to differ in both magnitude and temporal dependence to that observed in the sample during subsequent polings. The magnitude of the steady-state current eventually reached during the poling process was found to depend on temperature and is related to the mobility of charge. A sharp drop-off in SHG signal intensity that occurred when the poling electrodes were grounded is shown to result from the removal of surface charge that orients chromophore dipoles near the surface of the film; the decay in the macroscopic polarization that then occurs is prolonged by charges trapped in the polymer matrix. The build-up of trapped charge explains a memory effect in which the SHG signal relaxation time gradually increased as the film was subjected to multiple polings until a steady-state value was reached. Finally, it is demonstrated that the charges trapped in the polymer matrix are released only after the polymer is heated to high above its temperature of glass transition and the SHG signal has completely decayed away.

Poling Dynamics and Effects of Trapped Charge in Poled Polymer Films for Nonlinear Optical Applications

The behavior of surface and trapped charge that originates during contact electric-field poling of thin films of optically nonlinear polymers has been investigated. Thin films of poly(methyl methacrylate) doped with two different tricyanothiophene chromophores have been studied during and after the poling process by simultaneous measurement of the current through the poling circuit and the second harmonic generation signal (SHG) from the polymer system. The poling current present in a fresh sample was found to differ in both magnitude and temporal dependence to that observed in the sample during subsequent polings. The magnitude of the steady-state current eventually reached during the poling process was found to depend on temperature and was related to the mobility of charge. A sharp drop off in SHG signal intensity occurring when the poling electrodes were grounded is considered to be due to the removal of surface charge that orients chromophore dipoles near the surface of the film; the decay in the mac...

Controlling the structure of transparent Langmuir–Blodgett films for nonlinear optical applications

Langmuir–Blodgett (LB) multilayers of (E)-N-alkyl-4-[2-(4-docosyloxyphenyl)ethenyl]pyridinium bromide, CnH2n+ 1—Py+—CHCH—C6H4—O—C22H45Br–(dye I), are centrosymmetric (Y-type) for n⩽ 6 and non-centrosymmetric (Z-type) for 8 ⩽n⩽ 20. The areas obtained from grazing incidence synchrotron X-ray diffraction indicate that the molecules adopt a ‘stretched’ rather than a ‘U-shaped’ configuration and, unlike conventional amphiphilic materials, the long chain homologues do not invert during deposition. The second-harmonic intensity from films of the higher homologues (n 10) increases quadratically with the number of LB layers (I2ω(N)=I2ω(1)N2) whereas for the lower homologues (n⩽ 6) the intensity is negligible for even numbers of layers. The nonlinear optical properties of the sulfur (dye II), selenium (dye III) and quinolinium (dye IV) analogues are also reported and, in each case, quadratic enhancement of the second-harmonic intensity has been observed for suitable combinations of alkyl chain lengths. The second-order susceptibility, χ(2)zzz, of a 100 layer LB film of (E)-N-dodecyl-4-[2-(4-docosyloxyphenyl)ethenyl]quinolinium bromide (dye IV) is 20 pm V–1.

Design and synthesis of new ferroelectric liquid crystals. 14. An approach to the stereocontrolled synthesis of polar organic thin films for nonlinear optical applications

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDesign and synthesis of new ferroelectric liquid crystals. 14. An approach to the stereocontrolled synthesis of polar organic thin films for nonlinear optical applicationsDavid M. Walba, M. Blanca Ros, Noel A. Clark, Renfan Shao, Michael G. Robinson, Jian Yu Liu, Kristina M. Johnson, and David DoroskiCite this: J. Am. Chem. Soc. 1991, 113, 14, 5471–5474Publication Date (Print):July 1, 1991Publication History Published online1 May 2002Published inissue 1 July 1991https://doi.org/10.1021/ja00014a059RIGHTS & PERMISSIONSArticle Views189Altmetric-Citations67LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Langmuir-Blodgett films for nonlinear optical applications

Azo-benzene chromophores with an oxygen donor and five different end-groups have been attached to octadecyl chains or to polysiloxane backbones via hexadecyl spacer groups. These were deposited by the Langmuir-Blodgett (LB) technique using our own design of diamond-barrier trough. The LB deposition properties of the polymers were superior to those of the low molecular mass materials, which did not show second harmonic generation (SHG) as deposited monolayers. The strength of SHG from the polymers correlated with acceptor strength, but the maximum signal was only about 10% of that of hemicyanine. Only one of the polymers gave thick films of very high quality; this had a hydroxyl end-group and showed no SHG except when deposited from an acid subphase. This was presumed to result from protonation of the azo group to create an acceptor. The quality of the deposited films may correlate with their phase behaviour; the best material showed only a presumed soft crystalline phase. The film-forming properties of that film were remarkable; loss figures of around 2.5 dB cm−1 have been recorded at 633 nm in films of 1.3 Μm thickness. Future work will seek to isolate and independently control the factors involved in good film formation and in high SHG.